OAO, A-2, (Orbiting Astronomical Observatory A-2) Measurements of the Ultraviolet Airglow

The term airglow is commonly used to describe nonthermal emissions not correlated with magnetic disturbances in the upper atmosphere. The study of this radiation provides information on the nature of the upper atmosphere, as well as clues to the physical processes occurring at very high altitudes. The authors undertook an investigation to measure the dark and sunlit earth using the photometers of the Orbiting Astronomical Observatory A-2. The first series of measurements were concerned with the magnitude of the emitted radiation. Experimental results tend support the theory that dayglow in the 1300-1800A region is due primarily to photoelectron excitation of molecular nitrogen. The measurements obtained on the earths limb represent the most complete coverage known to the authors.